8295657: SA: Allow larger object alignments #10762

shipilev · 2022-10-19T12:04:49Z

Found this when working on JOL support (CODETOOLS-7903364). If you try to attach to VM running with -XX:ObjectAlignmentInBytes=32, then SA would fail with:

Caused by: java.lang.RuntimeException: Object alignment 32 not yet supported
at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.<init>(VM.java:510)
at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.initialize(VM.java:544)
at jdk.hotspot.agent/sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:444)

This code was added by JDK-6916623, but I don't see a reason why it should only handle 8 and 16 byte alignment.

Additional testing:

New regression test
Linux x86_64 fastdebug serviceability/sa, with the combination of:
- different -XX:ObjectAlignmentInBytes=: 8, 16, 32, 64, 128, 256
- different GCs: Serial, Parallel, G1
Linux x86_64 fastdebug sun/tools/jhsdb, with the combination of:
- different -XX:ObjectAlignmentInBytes=: 8, 16, 32, 64, 128, 256
- different GCs: Parallel, G1

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JDK-8295657: SA: Allow larger object alignments

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Thomas Stuefe (@tstuefe - Reviewer) ⚠️ Review applies to d332b97d
Chris Plummer (@plummercj - Reviewer)

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bridgekeeper · 2022-10-19T12:05:37Z

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openjdk · 2022-10-19T12:09:18Z

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serviceability

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mlbridge · 2022-10-19T12:13:41Z

Webrevs

01: Full - Incremental (6b49483e)
00: Full (d332b97d)

tstuefe

Looks fine. Curious, how well are all these alignments tested? E.g. do they work with all GCs?

test/hotspot/jtreg/serviceability/sa/TestObjectAlignment.java

openjdk · 2022-10-19T13:06:10Z

@shipilev This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8295657: SA: Allow larger object alignments

Reviewed-by: stuefe, cjplummer

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 16 new commits pushed to the master branch:

ef62b61: 8295703: RISC-V: Remove implicit noreg temp register arguments in MacroAssembler
6240431: 8295697: Resolve conflicts between serviceability/jvmti and nsk/jvmti shared code
1164258: 8295124: Atomic::add to pointer type may return wrong value
d3eba85: 8295414: [Aarch64] C2: assert(false) failed: bad AD file
028e8b3: 8137022: Concurrent refinement thread adjustment and (de-)activation suboptimal
faa6b66: 8295715: Minimize disabled warnings in serviceability libs
de1e0c5: 8295719: Remove unneeded disabled warnings in jdk.sctp
9612cf9: 8295529: Add link to JBS to README.md
b37421e: 8295564: Norwegian Nynorsk Locale is missing formatting
6707bfb: 8029633: Raw inner class constructor ref should not perform diamond inference
... and 6 more: https://git.openjdk.org/jdk/compare/9d0cfd1130b63f7acd67a52eb35c1ec38d43e514...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

shipilev · 2022-10-19T13:09:59Z

Looks fine. Curious, how well are all these alignments tested? E.g. do they work with all GCs?

I tested serviceability/sa with default (G1) and all acceptable alignments, seems to work fine. We can run the tests with other GCs, if anyone wants it.

plummercj · 2022-10-19T19:53:05Z

Looks fine. Curious, how well are all these alignments tested? E.g. do they work with all GCs?

We have gc/TestObjectAlignment.java. I don't see any indication that this test is not run with all GCs.

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/VM.java

plummercj · 2022-10-19T19:57:42Z

The short test isn't really proof that SA works well with these alternate alignments. You really should try running all SA tests with TEST_VM_OPTS=-XX:ObjectAlignmentInBytes=<n> where is something other than 8 or 16.

shipilev · 2022-10-19T20:26:33Z

The short test isn't really proof that SA works well with these alternate alignments. You really should try running all SA tests with TEST_VM_OPTS=-XX:ObjectAlignmentInBytes=<n> where is something other than 8 or 16.

As I stated in "Additional testing" in the PR description, I did ran serviceability/sa with different alignments. What other tests we should run?

plummercj · 2022-10-19T21:02:13Z

As I stated in "Additional testing" in the PR description, I did ran serviceability/sa with different alignments. What other tests we should run?

Sorry, I missed that. There are also some SA tests in test/jdk/sun/tools/jhsdb.

shipilev · 2022-10-20T09:35:16Z

Sorry, I missed that. There are also some SA tests in test/jdk/sun/tools/jhsdb.

Ran those too with different object alignments. I am running tests with different GCs too.

shipilev · 2022-10-20T12:10:09Z

Ran those too with different object alignments. I am running tests with different GCs too.

Ran with Serial, Parallel, G1. Shenandoah and ZGC have problems with SA tests even with default object alignment, so I skipped those. Serial OOMEs on some tests.

plummercj

Looks good.

shipilev · 2022-10-21T08:12:15Z

Thanks!

/integrate

openjdk · 2022-10-21T08:16:06Z

Going to push as commit dfd2d83.
Since your change was applied there have been 17 commits pushed to the master branch:

a345df2: 8280131: jcmd reports "Module jdk.jfr not found." when "jdk.management.jfr" is missing
ef62b61: 8295703: RISC-V: Remove implicit noreg temp register arguments in MacroAssembler
6240431: 8295697: Resolve conflicts between serviceability/jvmti and nsk/jvmti shared code
1164258: 8295124: Atomic::add to pointer type may return wrong value
d3eba85: 8295414: [Aarch64] C2: assert(false) failed: bad AD file
028e8b3: 8137022: Concurrent refinement thread adjustment and (de-)activation suboptimal
faa6b66: 8295715: Minimize disabled warnings in serviceability libs
de1e0c5: 8295719: Remove unneeded disabled warnings in jdk.sctp
9612cf9: 8295529: Add link to JBS to README.md
b37421e: 8295564: Norwegian Nynorsk Locale is missing formatting
... and 7 more: https://git.openjdk.org/jdk/compare/9d0cfd1130b63f7acd67a52eb35c1ec38d43e514...master

Your commit was automatically rebased without conflicts.

openjdk · 2022-10-21T08:16:29Z

@shipilev Pushed as commit dfd2d83.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

shipilev added 2 commits October 19, 2022 13:38

Basic fix

744f0aa

Simplify test

d332b97

openjdk bot added the rfr Pull request is ready for review label Oct 19, 2022

openjdk bot added the serviceability serviceability-dev@openjdk.org label Oct 19, 2022

tstuefe approved these changes Oct 19, 2022

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shipilev added 2 commits October 20, 2022 11:12

Merge branch 'master' into JDK-8295657-sa-obj-align

810a539

Drop range check

6b49483

plummercj approved these changes Oct 20, 2022

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openjdk bot closed this Oct 21, 2022

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shipilev deleted the JDK-8295657-sa-obj-align branch October 21, 2022 09:44

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8295657: SA: Allow larger object alignments #10762

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8295657: SA: Allow larger object alignments #10762

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